Rotary piston engine

ABSTRACT

The invention relates to a rotary piston engine of the type having an internally toothed ring and an externally toothed wheel which is orbitably and rotatably movable relative to the ring. The motor has a disk shaped valve which is driven by the externally toothed wheel through a universal joint shaft. In order that the shaft only applies torque to the valve, to the exclusion of any axially directed force, the valve has a splined bore and is journalled on a cylindrically shaped abutment which is fixed relative to the casing. The shaft has a splined head which engages the splined bore of the valve to effect rotation of the valve but the shaft head is in axial thrust engagement with the abutment so that no axial forces are transmitted to the valve. The valve and casing parts are appropriately and uniquely disigned with cooperating annular recesses so that axially directed hydraulic forces on the valve are also minimized. The overall result is that there is no mechanical axial loading of the valve and little or no hydraulic axial loading of the valve.

[151 3 ,680,987 51 Aug. 1, 1972 72] Inventor: Carl [541' ROTARY PISTON ENGINE V. Ohrberg, Denmark [73] Assignee: Danfoss A/S, Nordborg, Denmark [22] Filed: June 15, 1970 [21] App]. No.: 45,953

Havnbjerg,

[30] Foreign Application Priority Data Primary Examiner-Carlton R. Croyle Assistant Examiner.lohn J. Vrablik Att0rneyWayne B. Easton [5 7] ABSTRACT The invention relates to a rotary piston engine of the type having an internally toothed ring and an externally toothed wheel which is orbitably and rotatably movable relative to the ring. The motor has a disk shaped valve which is driven by the externally toothed wheel through a universal joint shaft. In order that the shaft only applies torque to the valve, to the exclusion of any axially directed force, the valve has a splined bore and is journalled on a cylindrically shaped abutment which is fixed relative to the casing. The shaft has a splined head which engages the splined bore of the valve to effect rotation of the valve but the shaft head is in axial thrust engagement with the abutment so that no axial forces are transmitted to the valve. The valvev and casing parts are appropriately and uniquely disigned with cooperating annular recesses so that axially directed hydraulic forces on the valve are also minimized. The overall result is that there is no mechanical axial loading of the valve and little or no hydraulic axial loading of the valve.

1 Claim, 3 Drawing Figures PATENTEmus 1 1912 I 3.680.987

' SHEET 1 (1F 3 ROTARY PISTON ENGINE The invention relates to a rotary piston engine, in which displacement chambers are formed between an externally toothed wheel and an internally toothed ring, and the toothed wheel is connected, through a universal joint shaft independent of the main shaft, to a rotary slide valve, which, together with a valve part connected to the toothed ring, forms a distributing valve, the universal joint shaft being connected, by means of a toothed portion, to the toothed wheel so that it rotates therewith.

German Patent Specification I 198750 discloses a rotary piston engine of this kind which can be used as a pump or a motor..In this engine the rotary movement of the toothed wheel is transmitted through a universal joint shaft to the main shaft (or vice versa). The charging and voiding cycle of the displacement chambers,

however, takes place at a considerably greater rate, i.e., at the speed of rotation of the center point of the toothed wheel about the center point of the toothed ring. For this purpose there is provided a sleeve-like rotary piston valve which is connected by way of a second universal joint shaft to the toothed wheel. It cooperates with apertures in the casing each of which leads to the root of a tooth. Distributed over the periphery of the rotary slide valve are openings which are alternately connected to the pressure and the low-pressure sides of the engine and the number of which is twice as great as the number of teeth on the toothed wheel. Both universal joint shafts are connected, by means of the toothed portion, to the toothed wheel so as to rotate therewith. In each case, the free ends of the universal joint shafts engage the main shaft and the sleeve-like rotary slide valve respectively, by way of link-pin connections.

Instead of the sleeve-like rotary valve, in which the effective apertures are disposed on a peripheral surface, it is often required to use a disc-shaped rotary slide valve, in which the effective apertures are contained in an end-face. In the case of a disc-shaped rotary slide valve, larger cross sections of aperture can be used, since the disc can be of greater diameter. Furthermore, the use of a disc-shaped rotary slide valve results in a reduction in the axial length of the construction. However, tests have shown that it is not possible to substitute, in the initially described rotary piston engine, a disc-shaped rotary slide valve for the sleeveshaped rotary slide valve while retaining the other features of the principle of construction. When this substitution was tried the system jammed and very heavy wear occurred.

The object of the invention is to provide a rotary piston engine of the initially described kind that is reliable in-operation and incorporates a disc-shaped rotary slide valve instead of a sleeve-shaped one.

According to the invention, this object is achieved by forming the rotary slide valve as a disc, by connecting the universal joint shaft to the rotary slide valve so that it rotates therewith and is enabled to execute axial movement, and by providing a stop, connected to the toothed ring, for that end-face of the universal joint shaft associated with the rotary slide valve.

This construction results from the surprising discovery that during the orbital movement of the center-point of the toothed wheel, the toothed construction between the wheel and the universal joint shaft leads to axial movement of this shaft and, in extreme cases, even to the universal joint shaft being pushed out of the wheel. If, in known manner, the universal joint shaft is connected to the rotary slide valve by way of a journal, this valve must also execute this axial movement. Such axial play waspermissible in the case of a sleeve-shaped rotary slide valve; a discshaped valve, however, must maintain its axial position, since otherwise the sealing effect ceases and jamming occurs. In accordance with the invention, only torque can be transmitted from the universal joint shaft to the rotary slide valve; the rotary slide valve does not however need-to take up axial forces. Instead, these axial forces are taken up by the stop. Consequently, the universal joint shaft cannot move out of the toothed wheel.

In the simplest case, the toothed ring and the stop are secured to the casing. The stop can simply be part of the casing.

Expediently, the universal joint shaft and the rotary slide valve can be interconnected to rotate with each other by means of a toothed arrangement. Then, both ends of the universal joint shaft can be of the same shape. As is well known, the toothed construction permits axial displacement.

To enable the universal joint shaft to engage roughly at the center of the rotary slide valve, it is advisable for the stop to take the form of a plug extending into the rotary slide valve.

If the diameter of this plug is the same as that of the bore of the rotary slide valve, the valve can be mounted on the plug. In contrast to mounting the valve by its periphery, this offers the advantage that only low circumferential speeds occur at the bearing.

In a further form of the invention, a cutoff passage in the rotary slide valve should lead from each control opening to the opposite face of the slide valve, and recesses that mirror the orifices in the valve part should be provided in the component bearing against said slide valve face. In this way pressure is relieved at the orifices in the valve part.

Furthermore, all even-numbered openings can be interconnected by an outerannular groove, and all oddnumbered openings by an inner annular groove in that end face of the rotary slide valve presented to the valve part, and these openings can be connected to the associated unions through annular grooves which have approximately the same radius as the first-mentioned annular grooves in the opposite component. In this way, those pressure effects stemming from the annular supply grooves are eliminated.

The rotary slide valve is then relieved overall not only of the mechanical forces stemming from the universal joint shaft, but also of the hydraulic forces deriving from the pressure medium.

An embodiment of the invention will now be described in greater detail by reference to the drawing, in which:

FIG. 1 shows a longitudinal section through a rotary piston engine designed in accordance with the inventron,

FIG. 2 is a cross-section on the line A-A of FIG. 1, and

FIG. 3 is a cross-section on the line B-B of FIG. 1.

The casing of the rotary piston engine illustrated consists of a bearing portion 1, an intermediate part 2, a side portion 3, an outer ring 4, a second side portion 5, a slide plate 6, a casing ring 7 and a connecting cover-plate 8. The parts 1-5 are interconnected by screw-bolts 9, and the parts 4-8 by screw-bolts 10. A main shaft 11 is mounted in bearings 12 and 13 in the bearing portion 1. A universal joint shaft 14, the two ends of which engage by an outer toothed portion with a corresponding inner toothed portion, connect the main shaft 11 to the internally toothed wheel 15. This toothed wheel is in an engagement with rollers 16, which are rotatably mounted in bearings 17 and 18 in the side portions 3 and and are arranged in recesses 19 in the outer ring 4, there being a clearance between the roller and the outer ring. Thus, between the teeth of a the toothed wheel 15, the roller 16, the other outer ring 4 and the two side portions 3 and 5, there are formed displacement chambers 20, which increase and diminish in size cyclically upon each revolution of the toothed wheel 15.

Sliding seals 21 are contained in grooves 22 in the outer ring 4, and are urged against the peripheral surface of each of the rollers 16 by a leaf spring 23 or the pressure obtaining in the chamber 24. In this way a perfect seal is achieved between adjacent displacement chambers 20 despite the clearance between each roller 16 and each recess 19.

The chambers 24 below the sliding seals 21 are interconnected by way of an annular groove 25 in the side portion 5. This annular groove communicates, by way of axial passages 26, with an annular groove 27, which in turn communicates, by way of two similar paths, with the unions 28 and 29 in the cover 8. Only one of these parts is shown. It consists of an axial bore 30 in the slide plate 6, a non-return valve 31 in the casing ring 7 and a connecting passage 32 in the cover 8. The non-return valve ensures that even if the engine operates on a reversible system, the side under higher pressure communicates with the chambers 24 each time.

An axial passage 33 in the side portion 5 terminates at a displacement chamber 20 between each two rollers 16, and each axial passage 33 is continued as an axial passage 34in the slide part 6. Since in the present case, nine rollers 16 are present, there are also nine such passages 33 and 34. Cooperating with the ends of the passages 34 is a rotary slide valve 35 which is driven at the same speed as the toothed wheel by a universal joint shaft 36, the two ends of which likewise engage by an outer toothed arrangement in a corresponding inner toothed arrangement. The rotary slide 35 is mounted on a plug 37 which is held in the cover 8. The rotary 'slide valve contains eight openings 38, which are connected to the union 28 by way of an annular groove 39,

and between each pair of these openings 38, the rotary slide valve contains eight openings 40 which are connected to the union 29 by way of an annular groove 41. In this way, the rotary slide valve 35 and the slide plate 6 constitute a commutating valve, which performs the function of connecting the displacement chambers 20 to the pressure or low-pressure side of the engine in the correct sequence.

To relieve the rotary slide valve of load, the openings 38 on the side opposite the annular groove 39 are inter- 28l$?fii3 ss ais ae zaa 5% 38932? 28F? connected by an annular groove 43. Also, opposite each of the passages 34, a surface 44, similar to the mouths is recessed in the cover 8, and a cut-off passage 45 leads from each opening 38,40 to an end-face of the cover 8, so that the same pressure obtains in the recesses 44 as at the mouths of the passages 34. The recesses 44 are shown in broken lines in FIG. 3; this Figure also shows that the cut-off passages 45 each have a widened portion 45a at the end face, which portion is equal to the width of the openings 38 and 40.

When the universal joint shaft 36 rotates, it can apply an axial pressure towards the right because of the toothed construction. This pressure is taken, up by the end face of the plug 37 and is therefore not transmitted to the slide valve 35. Since the slide valve is also largely relieved of pressure, it operates without jamming at all and with the least possible amount of friction.

All chambers into which a leakage oil can penetrate, particularly the central chambers 46, the bearing chamber 47 and the chamber 48 outside the rotary slide valve are interconnected through passages 49, 50 and 51. The cover 8 contains two non-return valves, not illustrated, by means of which leaking oil is passed in each case to the low-pressure unions.

I claim:

1. A rotary piston motor comprising a casing, an internally toothed ring in fixed relation to said casing, an externally toothed wheel cooperable with said ring and being orbitably and rotatably movable relative to the axis of said ring, a disk shaped valve mounted for rotation relative to the axis of said ring, said wheel and said valve each having a centrally disposed splined bore, a universal joint shaft having splined heads at opposite ends thereof in meshing engagement respectively with said wheel and valve splined bores, an abutment member in abutting engagement with an internal wall of said casing and extending part way into said splined bore of said valve for axial thrust engagement with the adjacent one of said splined heads, said abutment member having a cylindrically shaped surface in engagement with said valve bore for supporting said valve for rotation about the axis of said ring. 

1. A rotary piston motor comprising a casing, an internally toothed ring in fixed relation to said casing, an externally toothed wheel cooperable with said ring and being orbitably and rotatably movable relative to the axis of said ring, a disk shaped valve mounted for rotation relative to the axis of said ring, said wheel and said valve each having a centrally disposed splined bore, a universal joint shaft having splined heads at opposite ends thereof in meshing engagement respectively with said wheel and valve splined bores, an abutment member in abutting engagement with an internal wall of said casing and extending part way into said splined bore of said valve for axial thrust engagement with the adjacent one of said splined heads, said abutment member having a cylindrically shaped surface in engagement with said valve bore for supporting said valve for rotation about the axis of said ring. 